Method of improving the properties of certain explosives



Patented Feb. 16, 1954 METHOD OF IMPROVING THE BROPERTIES OF CERTAIN EXPLOSIVES Alfred '1. Blomquist, Fred '1. Fi'edcl'ek, and. James F. Ryan, Jr., Ithaca, N. Y., assignors to the United. States of America as represented by the Secretary of the Navy No Drawing. Application December 30,-. 1944, Serial No. 570,807

11 Claims.- (01. 260-467) .The present invention relates to the prepara-- tion of an explosive and more particularly to a new and improved method of purifying and stabilizing bis (EmitroXyeth yl) nitramine.

. Bis(2-nitroxyethyl)nitramine,'more briefl referred to by the trivial name Dina, is an ex plosive of particular interest as an essentially nonvolatile high potential plasticizer for nitrocellulose suitable for use in the production of certain types of propellants. The compound may be prepared by treating 1 mole of .diethanol amine with three moles of nitric acid in the presence of 3 moles-of acetic anhydride and about 0.05 mole of a chloride such as H01 as a catalyst.

In the manufacture of Dina on a large scale, its purifications and. stabilization present certain diificulties. Various batches of Dina produced by the process described above are not al-- ways uniform in quality and for this reason, some method of purification and stabilization of crude Dina may be required in order consistentl to produce a product that will pass a given Abel heat test, or one that will pass a given 100 C. vacuum stability test.

The purification of crude Dina has heretofore been. effected by passing steam for minutes through Dina maintained in the molten state under boiling water. Thereafter the water layer is decanted, the Dina is dissolved in acetone and the acetone solution is poured into av large volume of cold water containing a small. amount oil aqueous ammonia.

This original method. of purification, while satisfactory in certain. respects for a laboratory scale preparation, is characterized by certain disadvantages particularly when applied to large scale manufacture. In the first. place, the process in question is hazardous not only because it involves the use of aninfiammable volatile solvent (acetone)- in conjunction with a high explosive, but also because it involves heating to a relative- 1y high temperature an explosive which in the molten state is characterized under certain conditions by a sensitivity roughly corresponding to that of. nitroglycerine. Ai further disadvantage arises from the fact that successive batches of Dina purified in: this manner do not invariably pass a given Abel heat test or a given 100 C. vacuum stability test; i. e the purity andstability of successive batches, as judged on these conventional tests, are not satisfactorily uniform. The object of the present invention is to provide a new and improved method of purifying and stabilizing Dina.

A more particular object is the provision of a 2 purification and stabilization. procedure that en fects a greater improvement in the stability of crude Dina as reflected by the Abel heat testand the 100 vacuum stability test than that accomplished by the steaming process heretofore em-- ployed.

A further object is the provision of aninherentl-y safer method of puriiying and stabilizing crude Dina.

Other objects and advantages will be apparent as the invention ishereinafter more fully de scribed.

We have found that the foregoingobjects may be accomplished by passing air instead of steam 7 through a body of Dina maintained in the molten.

condition. under water heated above the melting. point ofv Dina (about 52 C.),- but below the boiling point of water. After the molten. Dina has been agitated under water by the passage of therethrough for a suitable time, the molten) aerated product is permitted to separate from the water, the aqueous layer is decanted and the Dina layer is preferably washed withfreshwater.- A small amount (less than 2%) of an aromatic amine capable of acting as a nitric oxide acceptor is then incorporated with the molten Dina. QlfiyS tallization of the aerated product is effected underwater by cooling. 3. vigorously agitated suspension of molten Dina in hot; water, to a tomperature below the melting. point of the purified and stabilized compound.

In order to describe the invention still more cl'earlyr two specific examples will hereinafter be described in considerable detail. It should be clearly understood, however, that this is done solely by way of example and is not intended either to delineate the scope" of the invention or to restrict the ambit-01 the appended claims.

EXAMPLE I Aeration with spontaneous cooling In a; jacketed Pyrex cylinder having a combat shaped bottom. measuring 2% diameter anct 9" in height, there was placed 200 g. of water and 100 g. of Dina- The temperature of the charge was raised to C. by passing steam through the jacket. Heating. was discontinued and. the contents agitated. by passing air into the bottom of the cylinder through a. glass tube. When the temperature had fallen to 56 the agitation was stopped and the water was siphoned on by gentle suction. The molten Dina was washed" with cc. of Water (50 0.)" and the Water again removed.

The molten Dina. was transferred to a glass 4 tailed procedures set forth in the specific examples. Thus for example, in lieu of Centralite-l (sym. diethyl diphenyl urea), Centralite-2 (sym. dimethyl diphenyl urea) or diphenyl amine may be used as the nitric oxide acceptor or stabilizer incorporated with the aerated Dina prior to crystallization. All such changes and T modifications are to be understood as included solid Dina was filtered, washed with 100 cc.'of

water, air dried and then desiccated in vacuum. EXAMPLE 2 Airing at controlled temperature In a jacketed Pyrex cylinder similar to that used in Example 1, there Was placed 200 g. of water (at 55 C., 65 0., 75 C., or 85 C.) and the selected temperature was maintained throughout the subsequent heating operation by regu-- lating the steam entering the jacket. The contents of the cylinder were agitated by a stream of air introduced through the glass tubeat the bottom of the container. To the water there was added in 2 minutes 100 g. of crude Dina and agitation of the resulting mixture was continued for 30 minutes after the addition. The air was then shut ofi and the water siphoned by gentle suction. The molten Dina was washed with 10!) cc. of water of the same temperature as that used in the heating operation, the washing operation being accomplished by agitating the molten Dina under water for 2 minutes using a stream of air. The wash water was removed by siphoning off with suction. The crystallization operation was similar to that described above in Example 1.

In order to demonstrate the relative efiectiveness of the present process as contrasted with the prior art method, a parallel series of experiments was carried out, starting in all cases with a' crude Dina prepared by astandardized procedure from the same stock of diethanol-amine. Several batches were purified by the prior art steaming procedure briefly described above. Other batches were purified by the process of Example 2 of the present specification, aeration taking place at 85 C. Representative stability data obtained in this series of experiments are given in the table.

TABLE I 4 I I V. S. at Experiment Purifirm- Amount Central- AHT 100 C No. itiou Method lite-l Added (g.) (min.) (e. c.

84-IV (E1). steaming 1 5 98-IV (Fl).-.. aeration 0 7.5 'E. C, QS-a: (F-1) do. 0.5/95.2 Din 12 98-VI (F-l) (10. 1.0/94.9 g. Din l5 0. 23 QBXI (F-1).. .do. 2.0/96 g. Dina 22.5

1 Steam passed through 100 g. molten Dina under nearly boiling water for 15 min.; steaming stopped and mixture permitted to stand min. at 97-90" 0.; water layer siphoned and Dine layer washed with 50 cc. boiling water; form a suspension oi the molten Dina in hotdygtcr containing a few drops of cone. sq. N'Ha: cool; filter; wash an y.

Process of Example 2, this specification.

E. C.=excccded capacity of test apparatus.

' The standardized procedure by which the Dina used in the foregoing tests was prepared, is described and claimed in the copending application of Blomquist and Fiedorek, Serial No. 570,804, filed of even date herewith.

It will be apparent to those skilled in the art that many variations may be made from the dewithin the scope of the appended claims.

We claim:

1. A method of purifying and stabilizing crude bis(2-nitroxyethyl)nitramine which comprises passing air through said crude material maintained in the molten state under water heated above the melting point of said nitramine but below about 95 0.; separating the molten nitramine from the water; adding to the molten nitramine a small proportion of an aromatic amine acceptor for oxides of nitrogen; forming a suspension of said molten nitramine in hot water; and then cooling said suspension until said molten Dina is crystallized.

2. The method of claim 1 wherein said aromatic amine comprises a dialkyl diphenylurea.-

3. The method of claim 1 wherein the water used in the first step of the process is maintained at a temperature between about 55 C. and about C.

4. The method of claim 1 wherein said aromatic amine comprises symmetrical diethyl diphenylurea.

5. In a method of purifying crude bls(2-nitroxyethyDnitramine the step which comprises passing a gas comprising oxygen through said crude material maintained in the molten state.

6.1m a method of purifying crude bis(2-nitroxyethyhnitramine the step which comprises passing air through said crude material maintained in the molten state under water heated above the melting point of said nitramine but below the boiling point of water.

7. A method of purifying and stabilizing crude bis(2-nitroxyethyl)nitramine which comprises aerating a molten mass of said nitramine under water, separating the molten nitramine from the water, and adding to the molten nitramine a small proportion of an amine acceptor for oxides of nitrogen.

8. A- method of stabilizing purified bis(2-nitroxyethyDnitramine which comprises adding to said nitramine a small proportion of an amine acceptor for oxides of nitrogen.

9. A method of stabilizing purified bis(2-n.itroxyethybnitramine which comprises adding to said nitramine in the molten state a small proportion of an aromatic amine acceptor for oxides of nitrogen, and then crystallizing said nitramine from suspension in water.

10. The method of claim 9 wherein said aromatic amine comprises symmetrical diethyl diphenylurea.

11. The method of claim 9 wherein aromatic amine comprises symmetrical dimethyl diphenylurea.

ALFRED T. BLOMQUIST. FRED T. FIEDOREK. JAMES F. RYAN, JR.

References Cited in the file of this patent OTHER REFERENCES Ellis: Chemistry 01 Petroleum Derivs, 1934, pp. 232, 276. (Copy in Div. 6.) 

5. IN A METHOD OF PURIFYING CRUDE BIS(2-NITROXYETHYL)NITRAMINE THE STEP WHICH COMPRISES PASSING A GAS COMPRISING OXYGEN THROUGH SAID CRUDE MATERIAL MAINTAINED IN THE MOLTEN STATE. 